Thanks to Navigation timing we now have a precise way of measuring front-end loading performance. We'll see how we can leverage Drupal to measure the time spent parsing HTML, applying CSS and initializing JS on a single page and over the whole website.

I will be presenting Navigation Timing as the W3C meant it to be, then explain the few differences we can find in browsers implementing the candidate recommendation. That will be an excuse to single out IE… in a good way.

After this I will show how to use Drupal to isolate HTML, CSS and JS processing times, with data validating the protocol that will be used in the rest of the presentation. I'll introduce a module with which we can automate the process and scale from a page to a whole website.

The last part of the talk will feature loading performance measurements of a few base theme available and a couple of things that we can find in contrib. There will be some data comparing the performance of Core JS after some of the changes that have been committed since January.

We've been walking in the dark about front-end performance for a long time. Why rely on instinct when we can rely on data. We'll be looking at loading performance, this session will not cover mobile JS profiling or debugging.